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sched: track the next-highest priority on each runqueue
We will use this later in the series to reduce the amount of rq-lock contention during a pull operation Signed-off-by: Gregory Haskins <ghaskins@novell.com>
This commit is contained in:
Gregory Haskins
parent
4d9842776a
commit
e864c499d9
@ -463,7 +463,10 @@ struct rt_rq {
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struct rt_prio_array active;
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unsigned long rt_nr_running;
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#if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED
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int highest_prio; /* highest queued rt task prio */
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struct {
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int curr; /* highest queued rt task prio */
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int next; /* next highest */
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} highest_prio;
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#endif
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#ifdef CONFIG_SMP
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unsigned long rt_nr_migratory;
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@ -8169,7 +8172,8 @@ static void init_rt_rq(struct rt_rq *rt_rq, struct rq *rq)
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__set_bit(MAX_RT_PRIO, array->bitmap);
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#if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED
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rt_rq->highest_prio = MAX_RT_PRIO;
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rt_rq->highest_prio.curr = MAX_RT_PRIO;
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rt_rq->highest_prio.next = MAX_RT_PRIO;
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#endif
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#ifdef CONFIG_SMP
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rt_rq->rt_nr_migratory = 0;
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@ -108,7 +108,7 @@ static void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
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if (rt_rq->rt_nr_running) {
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if (rt_se && !on_rt_rq(rt_se))
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enqueue_rt_entity(rt_se);
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if (rt_rq->highest_prio < curr->prio)
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if (rt_rq->highest_prio.curr < curr->prio)
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resched_task(curr);
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}
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}
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@ -473,7 +473,7 @@ static inline int rt_se_prio(struct sched_rt_entity *rt_se)
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struct rt_rq *rt_rq = group_rt_rq(rt_se);
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if (rt_rq)
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return rt_rq->highest_prio;
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return rt_rq->highest_prio.curr;
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#endif
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return rt_task_of(rt_se)->prio;
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@ -547,6 +547,21 @@ static void update_curr_rt(struct rq *rq)
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}
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}
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#if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED
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static struct task_struct *pick_next_highest_task_rt(struct rq *rq, int cpu);
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static inline int next_prio(struct rq *rq)
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{
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struct task_struct *next = pick_next_highest_task_rt(rq, rq->cpu);
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if (next && rt_prio(next->prio))
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return next->prio;
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else
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return MAX_RT_PRIO;
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}
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#endif
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static inline
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void inc_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
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{
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@ -558,14 +573,32 @@ void inc_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
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WARN_ON(!rt_prio(prio));
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rt_rq->rt_nr_running++;
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#if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED
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if (prio < rt_rq->highest_prio) {
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if (prio < rt_rq->highest_prio.curr) {
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rt_rq->highest_prio = prio;
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/*
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* If the new task is higher in priority than anything on the
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* run-queue, we have a new high that must be published to
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* the world. We also know that the previous high becomes
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* our next-highest.
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*/
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rt_rq->highest_prio.next = rt_rq->highest_prio.curr;
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rt_rq->highest_prio.curr = prio;
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#ifdef CONFIG_SMP
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if (rq->online)
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cpupri_set(&rq->rd->cpupri, rq->cpu, prio);
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#endif
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}
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} else if (prio == rt_rq->highest_prio.curr)
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/*
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* If the next task is equal in priority to the highest on
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* the run-queue, then we implicitly know that the next highest
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* task cannot be any lower than current
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*/
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rt_rq->highest_prio.next = prio;
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else if (prio < rt_rq->highest_prio.next)
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/*
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* Otherwise, we need to recompute next-highest
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*/
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rt_rq->highest_prio.next = next_prio(rq);
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#endif
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#ifdef CONFIG_SMP
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if (rt_se->nr_cpus_allowed > 1)
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@ -589,7 +622,7 @@ void dec_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
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{
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#ifdef CONFIG_SMP
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struct rq *rq = rq_of_rt_rq(rt_rq);
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int highest_prio = rt_rq->highest_prio;
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int highest_prio = rt_rq->highest_prio.curr;
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#endif
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WARN_ON(!rt_prio(rt_se_prio(rt_se)));
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@ -597,24 +630,32 @@ void dec_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
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rt_rq->rt_nr_running--;
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#if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED
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if (rt_rq->rt_nr_running) {
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struct rt_prio_array *array;
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int prio = rt_se_prio(rt_se);
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WARN_ON(rt_se_prio(rt_se) < rt_rq->highest_prio);
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if (rt_se_prio(rt_se) == rt_rq->highest_prio) {
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/* recalculate */
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array = &rt_rq->active;
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rt_rq->highest_prio =
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WARN_ON(prio < rt_rq->highest_prio.curr);
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/*
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* This may have been our highest or next-highest priority
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* task and therefore we may have some recomputation to do
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*/
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if (prio == rt_rq->highest_prio.curr) {
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struct rt_prio_array *array = &rt_rq->active;
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rt_rq->highest_prio.curr =
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sched_find_first_bit(array->bitmap);
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} /* otherwise leave rq->highest prio alone */
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}
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if (prio <= rt_rq->highest_prio.next)
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rt_rq->highest_prio.next = next_prio(rq);
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} else
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rt_rq->highest_prio = MAX_RT_PRIO;
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rt_rq->highest_prio.curr = MAX_RT_PRIO;
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#endif
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#ifdef CONFIG_SMP
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if (rt_se->nr_cpus_allowed > 1)
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rq->rt.rt_nr_migratory--;
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if (rq->online && rt_rq->highest_prio != highest_prio)
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cpupri_set(&rq->rd->cpupri, rq->cpu, rt_rq->highest_prio);
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if (rq->online && rt_rq->highest_prio.curr != highest_prio)
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cpupri_set(&rq->rd->cpupri, rq->cpu, rt_rq->highest_prio.curr);
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update_rt_migration(rq);
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#endif /* CONFIG_SMP */
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@ -1064,7 +1105,7 @@ static struct rq *find_lock_lowest_rq(struct task_struct *task, struct rq *rq)
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}
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/* If this rq is still suitable use it. */
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if (lowest_rq->rt.highest_prio > task->prio)
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if (lowest_rq->rt.highest_prio.curr > task->prio)
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break;
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/* try again */
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@ -1252,7 +1293,7 @@ static int pull_rt_task(struct rq *this_rq)
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static void pre_schedule_rt(struct rq *rq, struct task_struct *prev)
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{
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/* Try to pull RT tasks here if we lower this rq's prio */
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if (unlikely(rt_task(prev)) && rq->rt.highest_prio > prev->prio)
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if (unlikely(rt_task(prev)) && rq->rt.highest_prio.curr > prev->prio)
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pull_rt_task(rq);
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}
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@ -1338,7 +1379,7 @@ static void rq_online_rt(struct rq *rq)
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__enable_runtime(rq);
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cpupri_set(&rq->rd->cpupri, rq->cpu, rq->rt.highest_prio);
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cpupri_set(&rq->rd->cpupri, rq->cpu, rq->rt.highest_prio.curr);
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}
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/* Assumes rq->lock is held */
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@ -1429,7 +1470,7 @@ static void prio_changed_rt(struct rq *rq, struct task_struct *p,
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* can release the rq lock and p could migrate.
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* Only reschedule if p is still on the same runqueue.
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*/
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if (p->prio > rq->rt.highest_prio && rq->curr == p)
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if (p->prio > rq->rt.highest_prio.curr && rq->curr == p)
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resched_task(p);
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#else
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/* For UP simply resched on drop of prio */
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